Fluid heater



July 22, 1952 T. H. SHERMAN 2,604,084

FLUID HEATER Filed Nov. 10, 194'! '2 Sl-IEETS-SHEET 1 INVENTOR 72%0 .64jflfRMA/V July 22, 1952 T. H. SHERMAN 2,604,084

FLUID HEATER Filed Nov. 10, 1947 2 SHEETS-SHEET. 2

INVENTOR fie/46 b. JHEE/VAA/ Patented July 22, 1952 Tracy H.ShermanQSouth Nyack, Y; assignor' to Fost er Wheeler Corporation, NewYork,

N. Y., a corporation of New York Application November 10, 1947, SerialNo. 785,l06

This invention relates to heaters and more particularly to fluid heatersin which products of combustion flow in indirect heat exchangerelationship with fluid to be heated.

The present invention provides a heater for the conversion of fluids,particularly the conversion of hydrocarbon oil,'in which the fluid ispassed through a plurality of tubular members and the tubular membersare uniformly heated both circumferentially and longitudinally thereof.

This invention further provides a fluid heater which is efficient and ofrelatively simple constructlon.

This invention will be understood from the following description whenconsidered in connection with the accompanying drawings forming a partthereof and in which:

Fig. 1 is a Vertical sectional view taken on the line of Fig. 2;

Fig. 2 is a sectional plan view taken on the line '2-2 of-Fig. 1;

Fig. 3 is a view similar to Fig. 2 but taken on the line 33 of Fig. 1,and

Fig. 4 is a sectional plan view taken on the line 4-4 of Fig. 1.

Like characters of reference refer to the same or to similar partsthroughout the several views.

Referring to the drawings, the heater of the present invention comprisesa generally frustoconically shaped refractory shell or outer wall Inhaving a cylindrical portion I l at the top thereof and anothercylindrical portion l2 at the .base. The shell iorms'a combustionchamber I3 which is closed at the base by an annular refractory bottomI4. The shell is supported by girders l5 which are secured adjacent oneend thereof to portion I2 of the shell. The opposite endo f said girdersrest on foundation l6.

An annular row ofvertically disposed, spaced tubular members H, theoutside diameter of which row is slightly less than the inside diameterof upper portion ll extends longitudinally of the chamber. l3., Annularrow of tubular members I! forms the periphery of a passage which extendslongitudinally of the chamber [3.

The lower ends of the tubular. members pass through the bottom l4 andare in communication with an annular. lower header I8 to which the tubesare secured. Header I8 is supported by supporting members l9 cooperatingwith bottom plate l4. The upper ends of the tubular members ll extendbeyond the upper end of the shell H and communicate v with an annularupper header 2| to which the tubes are connected.

A cylindrical baffle plate or inner wall 22, having an outside diameterslightly less than .the diameter of the passage 20, is positioned withinthe passage 20'at the top thereof, said baffle plate extendingsubstantially vertically in the passage 10 Claims. (01. 122-333 andbeing longitudinally coextensive with the cylindrical portion ,ll .ofthe shell. A bottomf ring plate 23, throughwhich tubular members I!extend in a fluid' rtightmanner attire outer periphery thereof, issecurely mounted in 'flui'dtight relationship in the shell [0 and at theinner periphery thereof is secured in a fluid-tight manner to the baffleplate 22 thereby forming a bottom wall for, a passage or convectionheate ing chamber 24 the inner periphery of whioh'is formed by thebaffle plate '22 while the outer periphery thereof is formed by theinner surface of the cylindrical portion ll of Shell 10. The passage 24is closed at the. topithereof by an annular top plate 25, which is inthe form ofa ring, and is incommunication at the central portion thereofwitha flue 26.. Header 2i is enclosed by an enclosing box structure 2l.

A circular plate 2@ extends horizontally Within the cylindrical bafileplate 22. intermedia'te'the top and bottom thereof, the outer peripheryof plate 28 engagin'g'the, inner periphery of baffle 22 thereby forminga lower gas space 29 and an upper gas'space 3ll within the cylindrical baille plate 2'2., Lower gas ,space 29 which receivesgases from passage20, communicates with convection heating chamber 24 through a pluralityof elongated gas inlet openings 3!. They gas inlet open: ings extendlongitudinally through baffle 22 from a point beneath platev2 8 tothelower endof said bafile and-are, as shown(Fig..3) ,spaced' sub'stantially,9 0 from one another circumferentially of baflle 22. Uppergas space 30 is in communicationwithpassage 24 through a plurality ofgas outlet openings 32; which are similar to openings 3| but extend froma point adjacent the upper surface of plate-28.to theupper edge ofcyling drical baffle 22. The gas outlet openings 32, as shown (Fig. 4)are spaced substantial1y'{9 0 from onefanother, circumferentially ofhalite 22 and are so positioned in relationship to inlet openings 3! asto be substantially-equidistant between openings 3l,' or spacedsubstantially 4J5", from each of said openings '32 circumferentially ofthe cylindrical baffle 22.

The heater of the present invention is'fired by one or more burnersQ Asshown, burners 33 and are provided to fire the heater, burner 33 beingso disposed in relationship .to the chamber l3 as tofdirect a streamofgases of combustion to ,flow tangentially of said chamber and tubularmembers 11. The burner 33,, as lsh'ownmore particularly in Figs. 1 andZ,is mounted inthe shell Ill atone side ofth'ep'ortion l2 thereof sothat,a;.-s"tream of gases therefrom "will flow in afcircularjdirection,within the chamber l3. Other} burner 34 is mounted, in bottom 14. mm;setting and positioned centrally offpassage 'fil within the row oftubular me b rs ll! to direct fluid is withdrawn from header 2| throughoutlet pipe 36.

In operation, gases of combustion from burner 33 flow in a circulardirection within chamber l3 and in heat exchange relationship with theouter periphery of the circular row of tubular members I1. As the gasesrise, the diameter of the circular flow path of the gases of combustiongradually decreases due to the shape of shell [.0 and chamber l3; Gasesof combustion flowing from burner34'flow-verticallynpwardly in passagewithin the circular row oi'tubular members I! and passin heat exchangerelationship with the inner periphery of said row of tubes.

The gasesrof combustion flowing upwardly pass into lower gas space 29 ofcylindricalbaiile 22 and impinge on the under. surface of plate 28thereafter to flow into passage 24 through gas inlets 3|. The gasesentering passage 24 flow in clockwise and in counterclockwise directionsand also upwardly to enter gas outlet openings 32 at opposite sides of agas inletopeningil after passing in convection heat exchangerelationship with the upper portion of tubular members [1 within passage24. A portion of the gases from each gas inlet opening 3! will flow in acounterclockwise direction overtubes comprising a substantially 45portion of the circular row of tubular members before entering a gasoutlet slot 32 while another portion of the gases 'will flow in aclockwise direction over other tubes comprising another substantially 45portion of said circular row of tubes. From the gas outlets 32, thegases of combustion. enter upper gas space 30 above cylindrical baflle22 and flow outwardly of the setting through flue 26.

From the foregoing it will be readily understood that an efiicienttransfer of heat from the gases of combustion to the fluid flowingthroug the tubular members is attained. 1

- While the spacing of thegas inlets ill from one another and thespacing of the gas outlets 32 from one another has been shown anddescribed as substantially 90 andlthe spacing of the gas inlets andgas'outlets from one another has been set forth as substantially thespacing may be of a greater or lesser degree without departing fromtheinvention.

Changes may be made in the form, location and relative arrangement ofthe several parts of the arranged to form" an axial passage within the,

group, means for producing a stream of gases of combustion disposed inthe lower portion of the furnace to directsaid stream upwardly andlongitudinally of the axial passage, means forming a convection-heatingchamber around the upper portion of said tubes and extending axiallythereof, the annular outer wall forming the outer periphery of the,convection heating chamber, an annular inner, wall in spacedrelationship with the outer Wall and the tubular members and ex pendingaxially of said members, the space between the outer wall and the tubesand the space between the inner wall and'the tubes being such as tocause the gases to flow in heat exchange relationship with the tubularmembers in a confined space aroundsaid members, said convection heatingchamber being separated from the firstmentioned chamber and having aplurality of gas inlet and gas outlet openings, the gas inlet openingsbeing positioned to communicate with the lower portion of thefconvectionchamber and with said axial passage at a plurality ofcircumferentiallyspaeed'points and the gas outlet openings beingpositione'dftocommunicate with, the upper portion of the convectionchamber at a plurality of circumferentially'spacedpoints above andintermediate said. inlet openings, said inlet openings'and the outletopenings being spaced from one another such distance that a stream ofgases passing from an'inlet opening divides and the gases flow toadjacent outlet openings transversely of theupper portion of a pluralityof tubular members in a generally horizontal direc tion, a bailledisposed above the inlet openings, below the outlet openings and in thepath of flow of the gases in said first-mentioned chamber so as todirect said gases into theconvection section through said gas inletopenings, and gas outlet means for the furnace in communication withsaid gas outlet openings.

r 2. A furnace having a vertically extending circular chamber comprisingan annular outer wall, an annular row of spacedtubesspaced from theouter wall, said row being of lesser diameter than the chamber, thetubes being disposed to extend longitudinally of the chamber andarranged to surround an axial passage, means for producing a stream ofgases of combustion disposed in the lower portion of the furnace todirect said stream upwardly and longitudinally of the axial passage,means forming a convection heating chamber around the upper portion ofsaid tubes and extending axially thereof, the annular outer wall formingthe outer periphery of the convection heating chamber, said meanscomprising an annular inner wall of a diameter slightly less than thediameter of said annular row of tubes, a bottom wallthrough which thetubes extend arranged to close the bottom of the convection chamber in afluid-tight manner, and a top wall above the bottom wall in spacedrelationship thereto and arranged to close the top of said convectionheating chamber in a fluid-tight manner, the space between the outerwall and the tubes and the space between the inner wall and the tubesbeingsuch as tocause the gases to flow in heat exchange relationshipwith the tubular members in a confined space around said members, theinner wallhaving a' plurality of gas inlet and gas outlet openingstherethrough, the gas inlet openings being positioned in the lowerportion of the wall and spaced circumferentially from oneanother, thegas outlet openings being positioned in the upper portion of the wallabove the inlet openings and at spaced points intermediate said inletopenings, said inlet openings and the outlet openings being spaced fromone another such distance that a stream of gases pass ing from an inletopening divides and the gases flow to adjacentoutlet openingstransversely of the upper portion of a plurality of tubular members in agenerally horizontal direction, a baflle extending transversely of'theifirst-mentioned chamber in the path of flow of the gases *ofcombustion and disposed in fluid-tight relationship with said inner wallabove said inlet openings and below said outlet openings, and gas outletmeans for the furnace in communication with said gas outlet openings.

3. A furnace having a vertically extending circular chamber comprisingan annular outer wall, an annular row of spaced tubes spaced from theouter wall, said row being of lesser diameter than the chamber, thetubes being disposed to extend longitudinally of the chamber andarranged to surroundan axial passage, means for producing a stream ofgases of combustion disposed in the lower portion of the furnace todirect saidstream upwardly and longitudinallyof the axial passage, othermeans for producing astream ofgases of combustion, said other meansbeing disposedin the lower portion of the furnace chamber so as todirect a stream of gases of combustion tangentially of the furnacechamber and circumferentially of the annular row of tubes, means forminga convection heating chamber around the upper portion of said tubes andextending axially thereof, the annular outer wall forming the outerperiphery of the convection heating chamber, said means comprising anannular inner wall of a diameter slightly less than the diameter of saidannular row of tubes, a bottom wall through which the tubes extendarranged to close the bottom of the convection chamber in a fluid-tightmanner, and a top wall above the bottom wall in spaced relationshipthereto and arranged to close the top of said convection heating chamberin a fluid-tight manner,'the space between the outer wall and the tubesand the space between the inner wall and the tubes being such as tocause the gases to flow in heat exchange relationship with the tubularmembers in a confined space around said members, the inner wall having aplurality of gas inlet and gas outlet openings therethrough, the gasinlet openings being positioned in the lower portion of the wall andspaced circumferentially from one another, the gas outlet openings beingpositioned in the upper portion of the wall above the inlet openings andat spaced pointsintermediate said inlet openings, said inlet openingsand the outlet openings being spaced from one another such distance thata stream of gases passing from an in let opening divides and the gasesflow to adjacent outlet openings transversely of the upper portion of aplurality of tubular members in a generally horizontal direction, abaflle extending transversely of the first-mentioned chamber'in the pathof flow of the gases of combustion and disposed in fluid-tightrelationship with said inner wall above said inlet openings and belowsaid outlet openings, and gas outlet means for the furnace incommunication with said gas outlet openings. I e

4. A heater having a substantially vertically extending circular furnacechamber comprising an annular outer wall thetop of the chamber beingcylindrically shaped and of lesser diameter than the bottom of thefurnace, the portion of said chamber intermediate the top and bottombeing of frusto-conical shape, a substantially annular group of fluidconducting tubular members spaced from the outer wall, the tube groupbeing of slightly lesser diameter than said, top of the chamber andextending longitudinally of the furnace chamber, the tubes beingarranged to form an axial passage within the group, means forming aconvection heating chamber in said wall and the tubes and'the spacebetween the inner wall and the tubes being such as to cause the gases toflow in heat exchange relationship with the tubular members in aconfined space around said members, the inner wall having a plurality ofgas inlet and gas outlet openings therethrough, the gas inlet openingsbeing positioned in the lower portion of thewall and spacedcircumferentially from one another, the gas outlet openings beingpositioned in the upper portion of wall above the inlet openings and atspaced points intermediate said inlet openings, said in-, let openingsand the outlet-openings being spaced from one another 1 such distancethat a stream of gases passing from an inlet opening divides and thegases flow to adjacent outlet-openings transversely of the upper portionof. a plurality of tubular members in a generally horizontal direction,a baffle extending transversely of the firstmentioned chamber in thepath of flow of the gases of combustion and disposed in fluid-tightrelationship with said inner wall above said inletopenings and belowsaid outlet openings, means adjacent said bottom of the furnace forproducing a stream of products of combustion and disposed to direct saidgaseslongitudinally of the axial passage and toward the top of thefurnace, other means adjacent the bottom of the furnace chamber forproducing a stream of gases of combustion, said other means being sodisposed as to direct a stream of gases tangentially of said chamber andcircumferentially of the tube group, and gas outlet means incommunication with said gas outlet openings.

5. A furnace having .a vertically extending chamber comprising anannular outer wall, said chamber being substantially circular intransverse cross-section, a substantially annular group of fluidconducting tubulanmembers disposed in said chamber to extendlongitudinally thereof, said tubes being spaced from the outer wall andarranged to form an axial passage within the group, firing means forfiring the furnace disposed in the lower portion thereof, means forminga convection heating chamber around the upper portion of said tubes andextending axially thereof, the annular outer wall forming the outerperiphery of the convection heating chamber, an annular inner wall inspaced relationship with the outer wall and the tubular members andextending axially of said members, the space between the outer wall andthe tubes and the space between the inner wall and the tubes being suchas to cause the gases to flow in heat exchange relationship with thetubular members in'a confined space around said members, said convectionheating chamber being separated from the firstmentioned chamber andhaving a plurality of gas inlet and gas outlet openings, the gas inletopenings being positioned to communicate with the lower portion of theconvection chamber and with said axial passage at a plurality ofcircumferentially spaced points and the gas outlet openings beingpositioned to communicate with the upper portion of the: convectionchamber at a plurality of circumferentially spaced points above andintermediate said inlet openings, said inlet openings and the outletopenings being spaced from one another such distance that a stream ofgases passing from an inlet opening divides and the gases flow toadjacent outlet openings transversely of the upper portion of aplurality of tubular members in a generally horizontal direction, abaflie disposed above the inlet openings, below the outlet openings andin the path of flow of the gases in said first-mentioned chamber so asto direct said gases into the convection section through said gas inletopenings, and gas outlet means for the furnace in communication withsaid gas outlet openings.

6. A furnace having a vertically extending chamber comprising an annularouter wall, said chamber being substantially circular intransversecross-section, a substantially annular group of fluidconducting, tubular members disposed in said chamber to extendlongitudinally thereof,

said tubes being spaced from the outer wall and arranged to form anaxial passages within the 7 group, firing means for firing the furnacedisposed in the lower portion thereof, means forming a convectionheating chamber around the upper portion of said tubes and extendingaxially thereof, the annular outer Wall forming the outer periphery ofthe convection heating chamber, an annular inner wall in spacedrelationship with the outer wall and the tubular members and extendingaxially of said members, the, space between the outer wall and the tubesand the space between the inner wall and the tubes being such as tocause the gases to flow in heat exchange relationship with the tubularmembers in a confined space around said members, said convection heatingchamber being separated from the firstmentioned chamber and having aplurality of gas inlet and gas outlet openings, the gas inlet open ingsbeing positioned to communicate with the lower portion of the convectionchamber and with said axial passage at a plurality. of points spacedcircumferentially from one another substantially 90 and the gas outletopenings being positioned to communicate with the upper convectionchamher at a plurality of points above the inlet openings andspacedcircumferentiallyifrom one another substantially 90 and spacedcircumferentially from the inlet openings substantially 45, said inletopenings and the outlet openings being spaced from one another suchdistance that a stream of gases passing from an inlet opening dividesand the gases flow to adjacent outlet open-' ings transversely of theupper portion of a plurality of tubular members in a generallyhorizontal direction, a bafile disposed above the inlet openings, belowthe outlet openings and in the path of flow of the gases in saidfirst-mentioned chamber so as to direct said gases into the convectionsection through said gas inlet openings, and gas outlet means for thefurnace in communica tion with said gas outlet openings.

7. A heater having a substantially vertically extending circular furnacechamber comprising an annular outer wall the top of the chamber beingcylindrically shaped and of lesser diameter "than the bottom of thefurnace, the portion of said chamber intermediate the top and bottombeing of frusto-conical shape, a substantially annular group of fluidconducting tubular members spaced fromthe cuter wall, the group being ofslightly lesser diameter than said top of the chamber and extendinglongitudinally of the furnace'chamb'er, the'tubes' being arranged toform an axial passage within the group, firing means for firing thefurnace disposed in the lower portion thereof, means forming aconvection heating chamber in said top of the chamber extend ing aroundthe upper end of the tubes and axially thereof, the'annular outer wallforming the outer periphery of the convection heating chamber, anannular inner'wall in spaced relationship with the outer wall and thetubular members and extending axially of said members, the space betweenthe outer wall and the tubes and the space between the inner wall andthe tubes being such as to cause the gases to flow in heat exchangerelationship with the tubular members in a confined space around saidmembers, said convection heating chamber being separated from thefirstmentioned chamber and having a plurality of gas inlet and gasoutlet openings, the gas inlet openings being positioned tocommunicatewith the lower portion of the convection chamber and with said axialpassage at a plurality of circumferentially spaced points and the gasoutlet openings being positioned to communicate with the upper portionof the convection chamber at a plurality of circumferentially spacedpoints above and intermediate said inlet openings, said inlet openingsand the outlet openings being spaced from one another such distancethata stream of gases passing from an inlet opening divides and the gasesflow to adjacent outlet openings transversely of the upper portion of aplurality of tubular members in a generally horizontal direction, abaffle disposed above the inlet openings, below the outlet openings andin the path of flow of the gases in said first-mentioned chamber so asto direct said gases into the convection section through said gas inletopenings, and gas outlet means for the furnace in communication withsaid gas outlet openings.

8. A heater having a substantially vertically extending circular furnacechamber comprising an annular outer wall the top'of the chamber beingcylindrically shaped and of lesser diameter than the bottom of thefurnace, the portion of said chamber intermediatethe top and bottombeing of frusto-conical shape, a substantially annular group of fluidconducting tubular members spaced from the outer wall, the group beingof slightly lesser diameter than said top of the chamber and extendinglongitudinally of the furnace chamber, the tubes being arranged to forman axial passage within the group, firing means for firing the furnacedisposed in the lower portion thereof, means forming a convectionheating chamber in said top of the chamber extending around the upperend of the tubes and axially thereof, the annular outer Wall forming theouter periphery of the convection heating chamber, an annular inner wallin spaced relationship with the outer wall and the tubular members andextending axially of said members, the space between the outer wall andthe tubes and the space between the inner wall and the tubes being suchas to cause the gases to flow in heat exchange relationship with thetubular members in a confined space around said members, said convectionheating chamber being separated from the first-mentioned chamber andhaving a plurality of gas inlet and gas outlet openings, the gas inletopenings being positioned to communicate with the lower portion of theconvection chamber and with said axial passage at a plurality of pointsspaced circumferentially from one another substantially 90 and the gasoutlet openings being positioned to communicate with the upperconvection chamber at a plurality of points above the inlet openings andspaced circumferentially from one another substantially 90 and spacedcircumferentially from the inlet openings substantially 45, said inletopening and the outlet openings being spaced from one another suchdistance that a stream of gases passing from an inlet opening dividesand the gases flow to adjacent outlet openings transversely of the upperportion of a plurality of tubular members in a generally-horizontaldirection, a baflle disposed above the inlet openings, below the outletopenings and in the path of flow of the gases in said first-mentionedchamber so as to direct said gases into the convection section throughsaid gas inlet openings, and gas outlet means for the furnace incommunication with said gas outlet openings.

9. A furnace having a vertically extending circular chamber comprisingan annular outer wall,

an annular row of spaced tubes spaced from the outer wall, said rowbeing of lesser diameter than the chamber, the tubes being disposed toextend longitudinally of the chamber and arranged to surround an axialpassage, means for producing a stream of gases of combustion disposed inthe lower portion of the furnace to direct said stream upwardly andlongitudinally of the axial passage, other means for producing a streamof gases of combustion, said other means being disposed in the lowerportion of the furnace chamber so as to direct a stream of gases ofcombustion tangentially of the furnace chamber and circumferentially ofthe annular row of tubes, means forming a con-,

vection heating chamber around the upper portion of said tubes andextending axially thereof, the annular outer wall forming the outerperiphery of the convection heating chamber, said means comprising anannular inner wall of a diameter slightly less than the diameter of saidannular row of tubes, a bottom wall through which the tubes extendarranged to close the bottom of the convection chamber in a fluid-tightmanner, and a top wall above the bottom wall in spaced relationshipthereto and arranged to close the top of said convection heating chamberin a fluid-tight manner, the space between the outer wall and the tubesand the space between the inner wall and the tubes being such as tocause the gases to flow in heat exchange relationship with the tubularmembers in a confined space around said members, the inner wall having aplurality of gas inlet and gas outlet openings therethrough, the gasinlet openings being positioned in the lower portion of the wall andspaced circumferentially from one another substantially 90 and the gasoutlet openings being positioned in the upper portion of the wall abovethe inlet openings and spaced circumferentially of one anothersubstantially 90 and spaced circumferentially from the inlet openingssubstantially 45, said inlet openings and the outlet openings beingspaced from one another such distance that a stream of gases passingfrom an inlet opening divides and the gases flow to adjacent outletopenings transversely of the upper portion of a plurality of tubularmembers in a generally horizontal direction, a baflie extendingtransversely of the first-mentioned chamber in the path of flow of thegases of combustion and disposed'in fluid-tight relationship with saidinner wall above said inlet openings and below said outlet openings,

and, gas outlet means for the furnace in communication with said gasoutlet openings.

10. A heater having a substantially vertically extending circularfurnace chamber comprising an annular outer wall, the top of the chamberbeing cylindrically shaped and of lesser diameter than the bottom of thefurnace, the portion of said chamber intermediate the top andbottombeing of frusto-conical shape, a substantially annular group offluid conducting tubular members spaced from the outer wall, the tubegroup being of slightly lesser diameter than said top of the chamber andextending longitudinally of the furnace chamber, the tubes beingarranged to form an axial passage within the group, means forming aconvection heating chamber in said top of the chamber and around theupper end of the tubes the annular outer wall forming the outerperiphery of the convection heating chamber which chamber comprises anannular inner wall of a diameter slightly less than the diameter of saidannular row of tubes, a bottom wall through which the tubes extendarranged to close the bottom of the convection chamber in a fluidtightmanner, and a top Wall above the bottom wall in spaced relationshipthereto and arranged to close the top of said convection heating chamberin a fluid-tight manner, the space between the outer wall and the tubesand the space between the inner wall and the tubes being such as tocause the gases to flow in heat exchange relationship with the tubularmembers in a confined space around said members, the inner wall having aplurality of gas inlet and gas outlet openings therethrough, the gasinlet openings being positioned in the lower portion of the wall andspaced circumferentially from one another substantially and the gasoutlet openings being positioned in the upper portion of the wall abovethe inlet openings and spaced circumferentially of one anothersubstantially 90 and spaced circumferentially from the inlet openingssubstantially 45, said inlet openings and the outlet openings beingspaced from one another such distance that a stream of gases passingfrom an inlet opening divides and the gases flow to adjacent outletopenings transversely of the upper portion of a plurality of tubularmembers'in a generally horizontal direction, a baflle extendingtransversely of the first-mentioned chamber in the path of flow of thegases of combustion and disposed in fluid-tight relationship with saidinner wall above said inlet openings and below said outlet openings,means adjacent said bottom of the furnace for producing a stream ofproducts of combustion and disposed to direct said gases longitudinallyof the axial passage and toward the top of the furnace, other meansadjacent the bottom of the furnace chamber for producing a stream ofgases of combustion, said other means being so disposed as to direct astream of gases tangentially of said chamber and circumferentially ofthe tube group, and gas outlet means in communication with said gasoutlet openings.

TRACY H. SHERMAN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,881,275 I-Iuif Oct. 4, 19422,276,528 Throckmorton et al Mar. 17, 1942 2,514,279 Gleber July 4, 1950

